1. Technical Field
The present invention generally relates to a server computer operable in a client/server network system in which a plurality of client computers are connected via a communication line to a server computer. More specifically, the present invention is directed to a server computer capable of automatically notifying an updated content of a database to a relevant client computer which has once accessed this database before being updated, and also to a storage medium for recording thereon a program readable by this server computer.
2. Description of the Prior Art
Conventionally, in the case that a server computer provided in one conventional client server system contains a database for storing thereinto a plurality of records, this database is accessed by the respective client computers so as to download a desirable record selected from the plural records to the accessed client computers. Then, these client computers properly utilize the downloaded record.
Normally, the above-described download operation of this desirable record is carried out by operators of these client computers. Then, after the necessary record has been once downloaded in the relevant client computers, even when the relevant record saved in the database is updated later, the operators of these record-accessed client computers can hardly know, or grasp as to whether or not this relevant record is updated. Under such a circumstance, there are many possibilities that although the record contents of the database employed in the server computer have been already updated, the operators of the record-accessed client computers continuously use the old information records which were downloaded in the past.
To avoid such a problem, client computers may regularly check as to whether or not a record content of a database employed in a server computer is uploaded, and may newly download an updated record content if the first-mentioned record content has been updated. However, to achieve this update checking method, the respective client computers are required to regularly check the record contents of the database provided in the server computer. As a result, there is another problem that the work loads given to the respective client computers would be increased.
The present invention has been made to solve the above-described problem, and therefore, has an object to provide a server computer used in a client/server network system, capable of immediately notifying such information as to whether or not a storage content of a database is updated to a client computer when this client computer issues an access request to the database employed in the server computer.
To achieve the above-described object, a server computer, according to a first aspect of the present invention, is featured by such a server computer containing a database, in which in response to a data access request for the database issued from an arbitrary client computer among a plurality of client computers via a communication line, a content of data stored into said database is provided to the arbitrary client computer for issuing the access request, comprising:
history storing means for specifying a client computer which has issued a data access request via the communication line to the database and functions as an access source, and also for storing thereinto an access history of the specified client computer of the access source;
client computer extracting means for extracting such a client computer based upon the access history stored in the history storing means, the client computer having accessed the content of the database before being updated when the content of the database is updated; and
transmitting means for transmitting notification information used to notify the updated database to the client computer extracted by the extracting means.
Also, a server computer, according to a second aspect of the present invention, is featured by such a server computer in which a record accessed by at least one client computer within a database for storing thereinto a plurality of records is provided to the one accessing client computer, comprising:
history storing means for storing thereinto a history of access operation issued from the client computer with respect to each of the plural records every record stored in the database;
updating means for updating an arbitrary record which is required to be updated among the plural records stored in the database; and
transmitting means for transmitting notification information used to notify such a fact that the accessed record is updated among the plural records, to the client computer which has accessed the record before being updated.
Furthermore, a storage medium, according to a third aspect of the present invention, is featured by such a storage medium for storing thereinto a computer readable program code, wherein:
the program code is used to realize:
a function for specifying a client computer operable as an access source, which has issued an access request for accessing an arbitrary record via a communication line to a database containing a plurality of records;
a function for storing/managing an access history of the client computers which have accessed the records with respect to each of the records contained in the database;
a function for extracting all of client computers based upon the access history, the all client computers having accessed a record before being updated when the record contained in the database is updated; and
a function for transmitting notification information for notifying such a fact that the accessed record has been updated to all of the extracted client computers.
In accordance with the present invention, in the case that the storage content (record) of the database is updated, the client computer which has accessed this database in the past is automatically extracted, and furthermore, such a notification that the content of this database has been updated is automatically notified to this database-accessed client computer. As a result, an operator of this client computer can immediately recognize that the storage content of this database accessed in the past has been updated after the previous database access operation by receiving such a notification transmitted from the server computer. Therefore, this client server again accesses this updated database upon receipt of this notification, so that this operator of the client computer can grasp the latest storage content of this updated database.
As a consequence, operators of all of the client computers which have accessed the database saved in the server computer can continuously acquire the latest updated content of this database.